I like having machine-specific config in ~/.config/git, I think I'll do that. I 
didn't realize you could forward gpg-agent over a connection, I may look 
further into that.

Thanks for the help!

Joshua Nelson

On Sunday, March 11, 2018 17:21:42 EDT brian m. carlson wrote:
> On Sat, Mar 10, 2018 at 03:28:43PM +0000, NELSON, JOSHUA Y wrote:
> > Currently, `commit.gpgsign` allows you to give either 'true' or 'false' as
> > a value. If the key is not present, commits will fail:
> > 
> > ```sh
> > $ git commit -m "example"
> > error: gpg failed to sign the data
> > fatal: failed to write commit object
> > ```
> > 
> > I like to reuse my config file across several machines, some of which do
> > not have my GPG key. Would it be possible to add an option to sign the
> > commit only if the private key for `user.signingkey` is present? It could
> > be named something like `commit.gpgsign=default-yes`.
> Unfortunately, this isn't always possible.  You can forward the Unix
> socket for the agent over an SSH connection, at which point the remote
> machine has the ability to sign, but the gpg client doesn't list those
> as existing secret keys in its output (because technically, those keys
> don't exist on the remote system).  I use this technique at work, for
> example, to sign things on my development VM.
> 
> It might be possible to make the failure of the signing operation not be
> fatal in this case, although that could cause people to fail to sign due
> to transient failures even when the key is present on the system.
> 
> I usually handle this by storing my main configuration in ~/.gitconfig
> and on machines where I have a key, additionally having a
> ~/.config/git/config file that contains the commit.gpgsign entry.
> --
> brian m. carlson / brian with sandals: Houston, Texas, US
> https://www.crustytoothpaste.net/~bmc | My opinion only
> OpenPGP: https://keybase.io/bk2204